1. Field of Endeavor
The present disclosure is directed to a linear step motor.
2. Background
Generally, a step motor or a stepping motor is a digital actuator rotating or linearly moving at a predetermined angle, where a motor rotating at a predetermined angle is called a step motor while a motor moving linearly at a predetermined angle is called a linear step motor.
The linear step motor is advantageous in that a rotation angle can be precisely controlled due to the number of input pulses being in proportion to a rotation angle of motor. Thus, the linear step motor is largely used for Numerical Control machine or OA (Office Automation) devices such as industrial robots, printers and/or copiers.
In general, a linear step motor structurally includes a housing, a control part mounted outside of the housing, a stator part mounted inside the housing, a rotor module rotatably mounted inside the stator part by way of electromagnetic force, and a lead screw linearly mounted in association with a rotation motion of the rotor module.
Furthermore, the rotor module includes a magnet rotatably mounted inside a tooth yoke forming the stator part at a predetermined gap, and a nut shaft rotatably mounted inside the magnet in association with the magnet and formed with female screw threads. The lead screw is formed at a periphery with male screw threads meshed with the female screw threads of the nut shaft to enable a linear movement (forward and backward movement) in response to rotation of the nut shaft.
Meanwhile, the rotor module needs a wave washer, a spacer and an E-ring about a bearing mounted at a cover member in order to fix the nut shaft on the cover member opening/closing an opening of the housing at the linear step motor. In a case a plurality of assembly parts is needed, efficiency of assembly process may deteriorate, relevant parts may be lost in the assembly process and difficulty in parts management may arise due to maintenance of a large number of parts. Another problem is that parts may be omitted in the assembly process, such that improvement on assembly process of rotor module is badly required.